Applicable Systems
SUN2000
Symptoms
PV input reverse polarity detected. The inverter has detected that the PV input DC polarity is reversed. Thiscan damage the inverter if not corrected promptly.
Possible Causes
- PV array positive and negative cables connected to inverter negative and positive terminals respectively
- MC4 connectors cross-wired during installation
- PV combiner box internal wiring error
- Previous service or maintenance reversed cable connections
Troubleshooting Steps
- Step 1: Check the equipment status and fault indicators to confirm the active fault code
Fault indicator or HMI displays code 123 as active - Step 2: Verify all electrical connections, wiring harnesses, and connector seating
All connections secure, no corrosion, loose pins, or damaged wires - Step 3: Check the system diagnostic buffer or event log for detailed fault information
Diagnostic buffer shows the specific fault cause and timestamp - Step 4: Verify power supply stability and environmental conditions
Power supply stable, environment within specifications - Step 5: Restart the equipment or power-cycle the control system
Equipment restarts and enters normal operating state - Step 6: Contact manufacturer support if the fault persists after all checks
Support provides specific troubleshooting guidance
How to Reset
To reset: 1) Identify and fix the root cause described in the fault symptoms. 2) Press RESET on the HMI or controller, or power-cycle the equipment. 3) If the fault recurs, contact manufacturer service. Caution: Document the fault code and context before resetting.
Frequently Asked Questions
- Q: What does fault code 123 mean on the Huawei SUN2000?
Fault 123 on the Huawei SUN2000 indicates: PV input reverse polarity detected. The inverter has detected that the PV input DC polarity is reversed. This can damage the inverter if not corrected promptly. Refer to the equipment manual and manufacturer support for specific troubleshooting steps.
- Q: Can I continue operating the equipment with fault 123 active?
No. The equipment has detected a fault condition and has taken protective action (typically stopping or derating). Continuing to operate without fixing the root cause may cause further damage. Always investigate and fix the fault before resuming operation.
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Source: Huawei SUN2000 Series Inverter User Manual, Huawei Official Support (support.huawei.com)
Category: PLC & VFD
Published: 2026-10-03
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